Hooory shiiet you found it boyo! Though as to why it would be in models as opposed to assets (even though assets contain models...), that is strange. Some cleanup would be good for the pk3 files...
Like my other mod, if I make one about this, it will be for fun I just hope that the sfx stops with the animation rather than stopping at the end of the file, I remember it stopping mid loop so it should be fine
I am looking for rocket flight sound not initiation sequence before it's firing not sure where that might be I know where launch sound is but not the flight lol